'Red Dot Test' May Detect Preeclampsia Sooner

Test screens for abnormal proteins, similar to Alzheimer's research

ATLANTA -- A paper-based test may detect preeclampsia in a woman's urine by examining the same abnormalities in proteins used by Alzheimer's disease researchers, researchers said here.

The test is a small paper with a Congo red dot in the center, which remains a small red dot when the urine of a healthy pregnant woman is applied, but turns into a large red dot if she has preeclampsia -- most of the time, anyway.

Positive predictive value was 74% (95% CI 66%-83%), and negative predictive value was 91% (95% CI 88%-95%), reported Kara Rood, MD, of the Ohio State University in Columbus, and colleagues at the Society of Maternal Fetal Medicine (SMFM) annual meeting.

Rood explained during the presentation that Congo red dye is used as a prototype by researchers to identify amyloid plaques in the brains of Alzheimer's patients. The hypothesis was that the urine of pregnant women contains similar abnormally-folded proteins, which would be detected by this test. Therefore, the urine of healthy pregnant women would have no impact on the Congo red dye.

"When [examining the urine of] women with preeclampsia, the Congo red binds to the misfolded proteins and together, they travel to the periphery, dispersing in a larger-sized dot," she said, adding that the differences between a woman with or without preeclampsia are obvious, "enabling easy visual scoring."

There were 579 Congo red dot tests conducted on 346 women in the triage unit of Labor & Delivery at Ohio State University. Notably, 70% of women were at less than 36 weeks gestation and 46% were late preterm (34-36 weeks gestation). Overall, 89 women had a clinical diagnosis of preeclampsia following the Congo red dot test and 79% of those delivered preterm (median gestational age: 33 weeks, range: 21-36 weeks).

Additionally, there were 18 women who initially tested negative who then went on to have a positive Congo red dot test and clinical preeclampsia. There was a 14 day latency period (average 24 days, range: 4-35 days) between a positive test and delivery.

"Those with a positive Congo red dot test had significantly shorter intervals to labor and delivery compared to those who tested negative," said Rood.

The Congo red dye paper test was superior to other clinical tests in ruling out preeclampsia, including the laboratory "gold standard," Congo red dot nitrocellulose testing.

In a separate interview with MedPage Today, Rood said that they are currently in the process of commercialization and FDA approval for the Congo red dot test, as well as conducting other research on preeclampsia.

"We are currently working on further clinical trials in hopes to better identify women with preeclampsia in hopes of decreasing maternal morbidity and iatrogenic preterm birth rate," she said.

Concepts presented are the subject of patents and patent applications by Yale University and licensed to private entities for development and commercialization. Some of the authors are named as inventors of the Congo Red Dot Test.

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